Pump or motor



June 17, 1958 sTANSFlELD T L 2,839,008

PUMP 0R MOTOR 2 Sheets-Sheet 1 Filed July 20, 1955 June 17, 1958 u H.STANSFIELD ETAL PUMP 0R MOTOR 2 Sheets-Sheet 2 Filed July 20, 1955 m m mCaM 7913M, WW4 (0% United States Patent PUMP OR MOTOR The presentinvention relates generally to reciprocat ing piston pumps, motors, andcompressors.

It is an object of this invention to provide a reciproeating pistonpump, motor or compressor in which the components are disposed in abalanced relationship so as to eliminate axial thrust within the unit,and thereby eliminate the necessity of using thrust bearings and sealstherein.

P 'Another object of this invention is to provide, in such a pump, motoror compressor, improved pistons which are suitable for use with a barrelcam and which are constructed so as to nest around the barrel cam andthereby be prevented from turning in the cylinder bores.

A further object of this invention is to provide a pump,

motor or compressor of the type set forth above and in which the pistonsare double acting to provide a continuous flow of fluid for asubstantially smooth uninterrupted operation. Other objects'andadvantages will become apparent to those skilled inthe art as thefollowing detailed descrip. tion proceeds, taken in connection with theaccompanying drawings wherein: t

Figure 1 is a perspective view with parts cutaway of apump or motorembodying the present invention.

Fig. 2 is a diametric cross-sectional view of the illustrativeembodiment shown in Fig. 1.

:"Fig. 3 is a sectional view taken in the plane of line 3--3 of Fig. 2.

Fig. 4 is a sectional view taken in the plane of line 4 -4 of Fig. 2.

Fig.5 is a perspective view with parts cut away of the present inventionin. modified form for use as' a compressor. I

.Fig. 6 is a partialcross-sectionalview of the compressor shown in Fig;

Fig. 7 isa view taken in the plane of line 7-7 of Fig. 6. i

pFig. 8 is a partial cross-sectional view of a modified form of acompressor embodying the present invention. .Fig. 9 is a sectional viewtaken in the plane of line 99 of Fig. 8. gWhfle the invention issusceptible of various modifications and alternative constructions,certain preferred em bodiments have been shown in the drawings and willbe described below in detail, It should be understood, however,thatthere-is no intention to limit the invention to the specificrformsdisclosed, but, on the contrary, the intention-is to cover allmodifications and alternative constructions fallingwithin the spirit andscope of the invention as expressed in the appended claims.

;In accordance with the present invention, as illustrated in Fig. 1,there is provided a fluidpressure pump or motor device 20 which includesa pair of cylinder barrels 21 and 22 spaced axially apart on a rotatableshaft 24 and having a; plurality of circumferentially spaced, axiallydisposed cylinder bores, 25 and-26, respectively, thereil y, Thecylinder bores in one barrel are axially aligned with the cylinder boresin the other. barrel so there shown in a preferred balanced arrangement.

that a single piston is received in a pair of aligned bores.- An evennumber of these cylinder pairs are disposed in a circumferentiallyspaced relationship around the shaft. This disposition of the pistonsand cylinders results in opposing forces of equal magnitude ondiametrically opposite pistons, sothat the axial forces are balancedthereby eliminating an axial thrust on the shaft. The pistons 28reciprocate in the corresponding cylinder bore pairs and are operativelyconnected to a cam 29 which is secured to the shaft 24 intermediate thebarrels. The cylinder bores in which the pistons reciprocate areinterconnected through a suitable porting arangement so as to provide acontinuous flow of fluid when the device is acting as a pump or asmooth, non-pulsating motor action when the device is operating as afluid pressure actuated motor.

In the following description, the device 20 illustrating the presentinvention will be considered to be a pump in which the shaft 24 isrotated by a suitable power means in order to reciprocate the pistons 28in the cylinders 25 and 26 and thereby create a pumping action. It willbe appreciated, however, that upon the application of pressure fluid tothe device 20, the pistons will be reciprocated in the cylinders andwill rotate the shaft to drive the device as a motor.

Referring now to Fig. 2, the piston and cylinders are The cylinder bores25 and 26 are circumferentially positioned radially equi-distant fromthe axis of the barrels 21 and 22, and when the barrels are properlyoriented relative to each other, the corresponding cylinder bores ineach barrel are disposed directly opposite each other. A plurality ofpiston rods 28, corresponding in number to the bores in a single barrel,are slidably positioned in the respective bores 25 and 26 of the twospaced apart, confronting barrels 21 and 22. Both ends of each pistonrod are utilized as pistons, the piston surfaces and corresponding boresurf-aces being machined smooth and to a clearance sufficient to preventleakage of fluid between the piston and the cylinder bore wall.

End plates 31 and 32 are provided which, when mounted adjacent the outerends of these barrels cover the cylinder bore openings in these ends. Anaxial opening is provided in one of the plates 31 to rotatablyreceivethe shaft 24. The cylinder barrels and plates are assembled with thebarrels in a spaced-apart relationship with a cylindrical housing 34,disposed intermediate the barrels to form an enclosed chamber 35therebetween. A port 36, including a suitable pressure fluid fitting, isprovided in the center of the plate 32, not having the axial shaftopening, while a port 38, also including a pressure fluid fitting, issimilarly provided in the cylindrical wall 34.

The distributing valve arrangement for the pump has been constructed soas to utilize the rotary shaft as the moving part thereof for connectingthe cylinders alter-. nately to the inlet port duringthe intake orsuction stroke of the piston and to the discharge port during thepressing or discharge stroke of the piston. In order to form such avalve, sleeves 41 and 42 are pressed into the axial bores ofthe cylinderbarrels 21 and 22 respectively, and act as journals for the shaft'24which passes axially through the barrels. A plurality of channels arecut in the external surface of the sleeves so that when the sleeves areinserted in the axial bore of the cylinder barrels, passages are formedbetween the cylinder barrel and the sleeve for the transmission ofpressure fluid. .As shown in Fig. 3, outer channels 44 in the sleeves 41and 42 communicate with radial grooves 45 in the end plates. These:radial grooves ,45 communicate in turn with the outer ends of cylinderbores 25 and 26.. Similarly, as.

. shown in Fig; 4, inner channels 46 in the sleeves 41 and- 42communicate with radial grooves 48 in the inner end surface of thecylinder barrels 21 and 22. The grooves 48 communicate in turn with thechamber 35 which is formed between the cylinder barrels by the housing34.

The shaft 24, which forms the rotary portion of the control valve, isprovided with an axial bore 50 and two spaced segmental cut out portions51 and 52, displaced circumferentially 180 from each other on the shaftperiphery, and communicating with this bore. The bore 50 terminates atthe inner end of shaft 24, which inner end projects into a recessedportion 54 of plate 32. Port 36 provides an opening into the recess 48.Spaced apart segmental cutouts 61 and 62 on the periphery of the shaft24 are positioned intermediate andat a circumferential displacement of180 from the respective ad jacent cutout portions 51 and 52, each pairof the cutouts being located on the shaft in a position approximatingthat of a surrounding cylinder barrel. The intermediate cutouts arelocated so as to provide a communication between the inner and outerchannels 46 and 44 in the sleeves, radial ports through the sleevescommunieating with each channel being provided. Thus, as the shaft 24rotates, the cylinder bores 25 and 26 alternately communicate, throughthe outer sleeve channels 45 and the grooves 44 in the end plates, withthe port 36 in the end plate 32 by means of the segmental cutoutportions 51 and S2 and bore 50 in the shaft, and with the port 38 in thehousing 34 by means of the intermediate segmental cutout portions 61 and62 in shaft 24 which lead through the inner sleeve channels 46 and thebarrel grooves 48 into the chamber 35 formed by the housing 34.

The segmental cutout portions 51, 52, 61 and 62 of the shaft 24 are ofsufiicient size to communicate through the respective passages in thesleeves, with a cylinder bore during a substantial part of the inward oroutward stroke of the piston reciprocating therein.

Reciprocation of the rods and pistons in the cylinder bores isaccomplished by means of the barrel cam 29 having a cam track 64 on itsperipheral surface. Follower pins 65 depend from piston rods 28intermediate the ends thereof and are guided by the cam track 6 4 intowhich they are directed. The cam 29 is positioned between the cylinderbarrels 21 and 22 and is spaced therefrom by means of washers or gaskets66. The position of the cam track 64 on the cam must be correlatedrelative to the cutout portions 51, 52, 61 and 62 so as to permit theshaft to act as a rotating valve.

In other words, when the piston has reached the end of its suctionstroke, and is starting its discharge stroke, the particular cutoutportions on the shaft are positioned so that the cylinder communicateswith the discharge port of the pump. This action may be more readilyunderstood by reference to Fig. 1 of the drawings, and observing thepump action at the end including the suction or inlet port 36. The port36 in the end plate 32 will be assumed to be the suction port forpurposes of the present description, although it will appear that theoperation may be reversed to use this port as the discharge port bymerely reversing the direction of rotation of the shaft. When the pumpshaft 24 is rotating in the direction of the arrow, shown near the endof the shaft 24, one of the pistons 28, which is labeled A in theparticular instantaneous position shown, will be in the early stages ofits suction stroke. As the shaft rotates further, the piston A will moveaway from the end plate to create a suction in the cylinder bore26. Theouter segmental cutout portion 52 of the shaft 24 is then incommunication with both the inlet port 36 and the cylinder bore in whichthe piston A is creating a suction. Fluid which is supplied to the pumpinlet port 36 will then be drawn, through this cutout portion, into thecylinder .bore by the piston A.

Simultaneously with this suction or intake action of piston A, anotherpiston, such as the one labeled B, will be exhausting fluid which ithas-previously drawn 4 into its cylinder bore. This fluid is exhaustedthrough the inner segmental cutout portion 62 of the shaft, which isadjacent the outer segmental cutout portion, and into the chamberbetween the cylinder barrels 21 and 22. From this chamber the fluid isexhausted through the discharge port 38 in the housing 34 (Fig. 2).

The cam track, in this particular embodiment, is designed to reciprocatethe piston through one complete stroke, that is, a pressure or dischargestroke and a suction or intake stroke, for each revolution of the shaft.Thus the shaft makes a one-half or 180 revolution during the pressurestroke and a one-half or 180 revolution during the suction stroke of thepiston. Therefore, considering, for example, one end portion of thepump, the outer segmental portion 52 is displaced 180 from the innersegmental portion 62, and each segment includes, as a maximum, 180 ofthe shaft surface. With this arrangement, a single cylinder bore wouldcommunicate with the outer segment 52 during one-half of the completepiston stroke and with the inner segment 62 during the other half of thestroke.

For the practical purpose of effecting a pressure equalization in eachcylinder immediately prior to'the start of both the discharge andsuction strokes, the segments cover less than 180" of the surface,although they remain ,displaced 180 from each other. This leaves aslight land area 67 which will prevent direct communication between thecylinders and both the inlet and outlet ports during a short time at thebeginning of the suction and discharge strokes. Consequently, thepressure in the cylinder will increase to a value approximating the pumpdischarge pressure before the cylinder is connected to the dischargeport through one of the segments. This is known as precompression.Similarly, the suction pressure will in.- crease in a cylinder whichremains closed during the initial part of the suction stroke, and theresulting expansion will lower the pressure approximately to that of theinlet pressure when the cylinder and inlet are connected through theother segment. Thus, pulsation of pressure due to valve action, togetherwith the noise and other undesirable phenomena associated therewith, aresubstantially eliminated.

It should be kept in mind that the portion of the pump serving as theinlet and the portion serving as the-outlet depend entirely upon thedirection of rotation of the shaft.

In order to prevent the rotation of the pistons 28 in cylinder bores 25and 26, and to permit their nesting around the cam 29, segmentalportions are removed intermediate their ends to provide a recessedsurface 69. The follower pins 65 are inserted into the pistons in thecenter of the surface of the segmental cutout-portions. The peripheralsurface of the barrel cam 29 rides against the surface 69 of the cutoutportion of the respective pistons 28, as shown in Fig. 4. The amount ofmaterial longitudinally removed from the piston intermediate their endsneed only be sufiicient to permit the full stroke travel of the pistonsduring their reciprocation, and-must be deep enough to permit thenesting of the pistons around the barrel cam without causing them tobind thereto and interfere with the pumping action. The pins aredesirably mounted in bearings 71 secured within the pistons 28. The useof such a pin and bearing construction, permitting rotation of the pinsas they are guided by the cam, reduces the friction between the pins 65and the cam track 64 so that substantially all of the power input to thepump is converted to pumping energy.

When the cam track is at the proper angle relative to the shaft, it willbe apparent that upon application of pressure fluid to either of theports 36 or 38 the pistons 28 will be caused to reciprocate and the cam29 will thereby be driven by the pins 65 riding in the cam track 64. Theshaft, secured to the cam, will be rotated in turn by the cam andenergy'may be taken therefrom by a suitable means such as a gear orpulley.

it is under pressure or suction.

' V prevent the escape of air.

means of bolts 72 extending through suitable holes in the cylinderbarrels and plates, and which may be readily removed when it is desiredto replace a portion of the device. 3

Fig. 5 illustrates a modification of the present invention in which thedevice has been constructed to operate most efliciently as an aircompressor. In applications in which it is necessary to compress a fluidagainst an existing pressure head, valve means of the poppet type, forexample, which are positive in their action, are provided in thecompressor head in order to prevent leakage of the fluid when valves inthe end plates, along with suitable manifold channels, the basic pumpingmechanism previously described may be adapted for use as a compressor.In the following description reference numerals corresponding to thoseused in describing this basic mechanism will be used where applicablealong with the distinguishing In this modification the spaced barrelcylinders 21a and 22:: are provided at their outer endswith a dischargevalve plate 75 and a suction valve plate'76, containing the dischargevalves 78 andthesuction valves 79 respectively. The adjoining surfacesof these plates and the outer end surfaces of the cylinder barrels aremachined smooth to prevent leakage when the plates are assembled withthe barrels. This construction replaces the rotary valve previouslydescribed, the remainder of the device being constructed in the mannerdescribed above. Thus, the cylinder barrels are positioned in aspacedapart relationship so that pistons 28a may be reciprocated intheir respective cylinders 25a and 26a by means of a barrel cam 29awhich is secured to the drive shaft 24a. The pistons 28a nest around thecam 29a, the outer surface of which bears against the surface.

channel 82 communicating with the suctionports 81. A

port 84 and suitable fitting 85 provide means for connecting thisannular channel to the high pressure tank. Oneway poppet-type dischargevalves 78 are interposed between the discharge ports 81 and the annularmanifold channel 32 to pass the compressed fluid outwardly from thecompressor cylinders into the discharge channel 82. The intake ports 80,on the other hand, communicate directly with the atmosphere andareprovided with suitable poppet valves 78 permitting the flow of airinto the chambers but closing uponthe compression stroke to Thedischarge and suction valves 78 and 79 are biased to their seated orclosed position, shown in the drawings, by a coil spring 86 or the like.Tie bolts 70a are provided for holding the compressor in assembledrelation.

The compressor shown in Figs. 5, 6, and 7 is constructed for useespecially in compressing air. In cases or applications in which it isdesired to compress a gas other than air a manifold plate must beprovided having a suitable inlet attachment to accommodate thecompressor for such applications. 1

Referring now to Figs. 8 and 9, the manifold plate structure adapted tobe mounted on the outer ends of the barrel cylinders 21b and 22b hasbeen modified by providingthree plates, namelya discharge valve plate90, a suction valve plate 91, and a manifold plate 92. Discharge ports94 and suction ports 95 in the discharge valve plate 90 open into thecylinder bores 25b (Fig. 8). A valve seat is provided surrounding thedischarge ports 94 against which the discharge valves 98 seat.Similarly, the suction valve plate 91 is provided with suction Byproviding poppet ports 99 and discharge ports 100 leading from themanifold plate 92 and communicating with the suction ports 95 and thedischarge ports 94-, respectively, in the discharge valve plate 90.Valve seats are provided around the suction ports 99 in the suctionvalve plate against which the suction valves 101 seat. The manifoldplate 92, as can be seen in Figs. 8 and 9, is formed with two concentricannular channels 104 and 106. In the present modification the smallerdiameter channel 104 communicates with the high pressure head storagethrough a port 105 and serves as the discharge manifold. The largerdiameter channel 106, on the other hand, communicates, through a port107, with the fluid supply source and serves as the suction manifold.The suction ports 99 and the discharge ports in the suction valve platecommunicate with the suction manifold 106 and the discharge manifold104, respectively. The poppet valves 98 and 101 are, for example, of thepositive type spring biased one-way poppet valves.

In each of the compressor modifications, only a portion of the devicehas been shown, although it will be apparent upon examination of thedrawings that similar valve and manifold plates are provided on each endof the compressor unit. The compressors are therefore double acting withthe same advantageous thrust eliminating characteristics.

We claim as our invention:

l. In a pressure fluid pump or the like, the combination comprising ahousing defining a plurality of pairs of aligned cylinders arranged incircumferentially spaced relation, a shaft rotatably mounted in saidhous ing, a barrel cam mounted on said shaft intermediate the opposedends of said cylinders, a double acting piston reciprocably mounted ineach of said pairs of cylinders,

each piston having an intermeidate segmental recess for cooperating withsaid barrel cam to prevent rotation of said piston in said cylinders,means on said piston and within said recess for operatively engagingsaid cam, said housing having a first pressure fluid port intermediatesaid pairs of cylinders and a second pressure fluid port alined axiallywith said shaft, and means for distributing pressure fluid to and fromsaid cylinders through said housing ports as an incident to the relativerotation of said shaft and said housing comprising a pair of sleevesaxially alined in said housing corresponding to said pairs of cylindersand journaling said shaft for rotation, said sleeves having a pluralityof ports communicating with said cylinders and a plurality of portscommunicating with said first housing port, said shaft having a passageextending substantially axially therein and in communication with saidsecond housing port, and said shaft having segmental cut-out portionsfor conmeeting said sleeve ports from said cylinders alternately to saidfirst housing port and to said second housing port as said shaftrotates.

2. In a pressure fluid pump or the like, the combination comprising ahousing defining two groups of cylinders of each group being arranged incircumferentially spaced relationand the cylinders of one group beingdisposed in opposed relation to those of the other group and alignedtherewith, a plurality of double acting pistons having the opposite endsthereof respectively received in corresponding cylinders of each group,a shaft coaxially disposed with respect to said groups of cylinders androtatable with respect thereto, a barrel cam mounted upon said shaftintermediate said groups of cylinders and having an operative connectionwith each of said pistons for effecting reciprocation thereof in saidcylinders upon relative rotation of said shaft and said housing, saidconnection between said cam and said pistons including means forconstraining said piston to longitudinal movement, said housing having afirst pressure fluid port intermediate said pairs of cylinders and asecond pressure fluid port alined axially with said shaft, and

means for distributing pressure fluid to and from said cylinders throughsaid housing ports as an incident to the relative rotation of said shaftand said housing comprising a pair of sleeves axially alined in saidhousing corresponding to said pairs of cylinders and journalling saidshaft for rotation, said sleeves having a plurality of portscommunicating With said cylinders and a plurality of ports communicatingwith said first housing port, said shaft having a passage extendingsubstantially axially therein and in communication With said secondhousing port, and said shaft having segmental cut-out portions forconnecting said sleeve ports from said cylinders alternately to saidfirst housing port and to said second housing port as said shaftrotates.

3. In a pressure fluid pump or the like, the combination comprising ahousing defining a plurality of pairs of aligned cylinders arranged incircumferentially spaced relation, a bore extending through said housingaxially of said pairs of cylinders, a pair of sleeves press-fitted insaid bore corresponding to said pairs of cylinders, a shaft rotatablymounted in said sleeves coaxially with said pairs of cylinders, a barrelcam fixed on said shaft and having a cam slot in the peripheral surfacethereof, said cam being disposed intermediate the opposed ends of saidcylinders, a double acting piston reciprocably mounted in each of saidpairs of cylinders, each piston having a segmental recess intermediateits ends for cooperating with said barrel cam to prevent rotation ofsaid piston in said cylinders, means rotatably mounted on said pistonand within said recess for operatively engaging in said cam slot foreffecting reciprocation of said piston in said cylinders upon relativerotation of said shaft and said housing, said housing having a firstpressure fluid port intermediate said pairs of cylinders and a secondpressure fluid port axially alined with said shaft, said sleeves havinga pluality of ports communicating with said cylinders and a plurality ofports communicating with said first housing port, said shaft having apassage extending substantially axially therein and in communicationwith said second housing port, and said shaft having segmental cutoutportions for connecting said sleeve ports from said cylindersalternately to said first housing port and to said second housing portas an incident to the relative rotation of said shaft and said sleeves.

4. In a pressure fluid pump or the like, the combination comprising ahousing defining a plurality of pairs of alined cylinders arranged incircumferentially spaced relation, a shaft rotatably mounted in saidhousing, a barrel cam mounted on said shaft intermediate the opposedends of said cylinders, a double acting piston reciprocably mounted ineach of said pairs of cylinders, each piston having an intermediatesegmental recess for cooperating with said barrel cam to preventrotation of said piston in said cylinders, means on said piston andWithin said recess for operatively engaging said cam, said housinghaving a first pressure fluid port intermediate said pairs of cylindersand a second pressure fluid port axially alined With said shaft, andmeans for distributing pressure fluid to and from said cylinders throughsaid housing ports as an incident to the relative rotation of said shaftand said housing comprisinga pair of sleeves axially alined in saidhousing corresponding to said pairs of cylinders and journaling saidshaft for rotation, said sleeves having a plurality of portscommunicating with said cylinders and a plurality of ports communicatingwith said first housing port, said shaft having a passage extendingsubstantially axially therethrough in communication with said secondhousing port, and said shaft having pairs of segmental cut-out portionsfor connecting said sleeve ports from said cylinders alternately to saidfirst housing port and said second housing port as said shaft rotates,the segmental cut-out portions of each pair being spaced substantiallyapart from each other.

5. In a pressure fluid pump or the like, the combination comprising ahousing defining a plurality of cylinders arranged in circumferentiallyspaced relation and opening into a space of circular cross-section, ashaft rotatably mounted in said housing and extending axially of saidcylinders, a barrel cam mounted on said shaft and in said housing space,a piston reciprocably mounted in each of said cylinders, each pistonhaving a segmental recess for cooperating with said barrel cam toprevent rotation of said piston in said cylinder, means on said pistonand within said recess for operatively engaging said cam, said housinghaving a first pressure fluid port opening into said space and a secondpressure fluid port axially alined with said shaft, and means fordistributing pressure fluid t0 and from said cylinders through saidhousing ports as an incident to the relative rotation of said shaft andsaid housing comprising a sleeve axially alined in said housingcorresponding to said cylinders and journaling said shaft for rotation,said sleeve having a plurality of ports communicating with saidcylinders and a plurality of ports communicating with said first housingport, said shaft having a passage extending substantially axiallytherein and in communication with said second housing port, and saidshaft having segmental cut-out portions connecting said sleeve portsfrom said cylinders alternately to said first housing port and saidsecond housing port as said shaft rotates in said housing.

References Cited in the file of this patent UNITED STATES PATENTS1,339,276 Murphy May 4, 1920 2,070,880 Blum Feb. 16, 1937 FOREIGNPATENTS 610,428 Great Britain Oct. 15, 1948

